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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "platform/audio/FFTConvolver.h"
#include "platform/audio/VectorMath.h"
namespace blink {
using namespace VectorMath;
FFTConvolver::FFTConvolver(size_t fftSize)
: m_frame(fftSize),
m_readWriteIndex(0),
m_inputBuffer(fftSize), // 2nd half of buffer is always zeroed
m_outputBuffer(fftSize),
m_lastOverlapBuffer(fftSize / 2) {}
void FFTConvolver::process(FFTFrame* fftKernel,
const float* sourceP,
float* destP,
size_t framesToProcess) {
size_t halfSize = fftSize() / 2;
// framesToProcess must be an exact multiple of halfSize,
// or halfSize is a multiple of framesToProcess when halfSize >
// framesToProcess.
bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);
ASSERT(isGood);
if (!isGood)
return;
size_t numberOfDivisions =
halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;
size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;
for (size_t i = 0; i < numberOfDivisions;
++i, sourceP += divisionSize, destP += divisionSize) {
// Copy samples to input buffer (note contraint above!)
float* inputP = m_inputBuffer.data();
// Sanity check
bool isCopyGood1 = sourceP && inputP &&
m_readWriteIndex + divisionSize <= m_inputBuffer.size();
ASSERT(isCopyGood1);
if (!isCopyGood1)
return;
memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);
// Copy samples from output buffer
float* outputP = m_outputBuffer.data();
// Sanity check
bool isCopyGood2 = destP && outputP &&
m_readWriteIndex + divisionSize <= m_outputBuffer.size();
ASSERT(isCopyGood2);
if (!isCopyGood2)
return;
memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);
m_readWriteIndex += divisionSize;
// Check if it's time to perform the next FFT
if (m_readWriteIndex == halfSize) {
// The input buffer is now filled (get frequency-domain version)
m_frame.doFFT(m_inputBuffer.data());
m_frame.multiply(*fftKernel);
m_frame.doInverseFFT(m_outputBuffer.data());
// Overlap-add 1st half from previous time
vadd(m_outputBuffer.data(), 1, m_lastOverlapBuffer.data(), 1,
m_outputBuffer.data(), 1, halfSize);
// Finally, save 2nd half of result
bool isCopyGood3 = m_outputBuffer.size() == 2 * halfSize &&
m_lastOverlapBuffer.size() == halfSize;
ASSERT(isCopyGood3);
if (!isCopyGood3)
return;
memcpy(m_lastOverlapBuffer.data(), m_outputBuffer.data() + halfSize,
sizeof(float) * halfSize);
// Reset index back to start for next time
m_readWriteIndex = 0;
}
}
}
void FFTConvolver::reset() {
m_lastOverlapBuffer.zero();
m_readWriteIndex = 0;
}
} // namespace blink
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